Optimal Dynamic Framed Slotted ALOHA Based Anti-collision Algorithm for RFID Systems

In Radio Frequency IDentification (RFID) system, one of the most important issues that affect the data integrity is the collision resolution between the tags when these tags transmit their data to reader. In majority of tag anti-collision algorithm, Dynamic Framed Slotted Aloha (DFSA) has been employed as a popular collision resolution algorithm to share the medium when multiple tags respond to the reader’s signal command. According to previous works, the performance of DFSA algorithm is optimal when the frame size equals to the number of un-identified tags inside the interrogation zone. However, based on our research results, when the frame size equals to number of tags, collision occurs frequently, and this severely affects the system performance because it causes power consumption and longer tag reading time. Since the proper choice of the frame size has a great influence on overall system performance, in this paper we develop an analytical model to study the system throughput of DFSA based RFID systems, and then we use this model to search for an optimal frame size that maximizes the system throughput based on current number of un-identified tags. In addition to theoretical analysis, simulations are conducted to evaluate its performance. Comparing with the traditional DFSA anti-collision algorithm, the simulation results show that the proposed scheme reaches better performance with respect to the tag collision probability and tag reading time.